Crop protection



June 27, 1967 J. 5. BROWN CROP PROTECTION Filed July 51, 1964 //v l fA/Toe L/%m 5 Wm eriww 7702/1/47 United States Patent 3,327,505 CROP PROTECTION John S. Brown, Flossmoor, 111., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana Filed July 31, 1964, Ser. No. 386,779 1 Claim. (Cl. 67-21) This invention relates to the protection of plants susceptible to injury by low ambient air temperatures. More particularly it relates to the protection of agricultural crops against frost damage.

Protection of living plants against freezing temperatures and resultant frost damage is of paramount importance to fruit growers, vegetable farmers, and ornamental nurserymen. Freezing temperatures can occur at any time depending upon the area as a result of a generalized cold snap or very localized where cold and warm air stratifies. Frost damage to fruit trees can destroy the trees, blooms or maturing fruit. Likewise, vegetable crops can be destroyed \at any time as well as ornamental flowers, shrubs, and trees.

Various means have been used to combat frost damage when falling temperatures threaten. The most widespread method has been to burn solid and liquid combustible materials in the locus of the living plants to warm the ambient air. It is well known that incomplete combustion of such materials can cause plant damage as well as create serious air pollution problems and road hazards by the smoke produced. Liquid fuels require a substantial capital investment in mechanical burners, storage, and delivery equipment that is costly to maintain and operate. A lowcost solid fuel that is clean burning without smoke and which can be easily handled and stored in the field ready for use is desired to replace solid materials such as old tires and the liquid fuels such as heater oils.

In accordance with the present invention, an improved solid fuel is provided that can be burned in the locus of the plants susceptible to injury by low ambient air temperatures and thereby minimize possible frost damage. The solid fuel of the invention consists of the combination of solidifiable wax and an oiland water-resistant paper container therefor. The wax and container have dilferential burning rates after ignition so that the container burns at a lesser rate than the wax to provide a reservoir for molten wax during the combustion period. It burns cleanly without smoke and is completely consumable so that no residue is left in the field. Further, the solid fuel of the invention can withstand the weathering effects of rain and sun in the field and be ready for use at all times. The fuel can be easily ignited by any known means such as a small amount of grass on the top surface of the wax or by a 'blowtorch.

The wax component of the present solid fuel can be any known wax of plant, animal, or mineral origin. Especially useful waxes are the petroleum waxes melting in the range of from about 95 to 200 F. Such hydrocarbon waxes may be refined or unrefined having an oil content of 0l5 percent, and which are solid at ordinary temperatures.

It has been discovered that long fiber kraft paper that has all surfaces coated with a polyolefin such as polyethylene, polypropylene or mixtures thereof or copolymers of ethylene or propylene and other polymerizable monomers provides the desired differential burning rate between the wax and the container. Such coated paper is oiland water-resistant, thereby maintaining its structure during exposure to rain and elevated temperatures, at which temperatures some of the wax may melt, in the field. The shape of the container can be cubical, rectangular or cy- Patented June 27, 1967 ice lindricai being completely closed or an open-top. It has been found that a cylindrical container having a wall thickness of from about 30-50 'point and a bottom of about -100 point thickness heat sealed to the wall provides the requisite structural, storage and burning properties.

In the drawing an embodiment of this invention is illustrated wherein:

FIG. 1 is a perspective view of a solid fuel unit; and

FIG. 2 is a vertical cross-sectional view of the solid fuel unit of FIG. 1.

A plurality of solid fuel units 12 were prepared by melting an unrefined petroleum wax 13 having a melting point range of from about 105 to 115 F., and an oil content of from 2 to 6% and pouring the molten wax into opentop cylindrical paper containers 14 having a diameter of about 10 inches and a wall height of from 10 to 16 inches, to give solid fuel units of from 27 to 40 lbs. of wax. The paper used had a polyolefin coating 17. The long fiber kraft paper had a 45 point thickness for the wall 15 and point thickness for the bottom 16. After the wax solidified, several units were stored unprotected in the open exposed to rain and sun for about two months at temperatures ranging from about 70 to F. Additional units were stored in a greenhouse where the average temperature ranged from to F. and these units were sprayed with water each day for about four weeks. At the end of the respective storage periods, the solid fuel units showed no damage from water or loss of wax even though elevated storage periods melted some of the wax.

Ignition of some of the containers produced a flame across the top of the wax. The molten wax formed during burning was held in the container by the differential burning rates of the wax and paper so that no wax was lost from the container during. combustion. When the flame was snuffed out simply by inverting a pail over the unit, the molten wax then solidified without any loss nor impairment to the container. The partially used units can then be reused at any time. No smoke formed during the combustion period nor was there any ash or residue found :after completely burning.

Any paper stock having the requisite strength and lesser burning rate than the wax can be used provided it has been rendered oiland water-resistant.

It will be apparent to one skilled in the art that the present invention provides a simple and low-cost solid fuel that can be used to protect living plants from injury by freezing temperatures. The solid fuel can be economically used to protect fruit orchards, berry, and vegetable producing areas as well as for ornamental flowers, etc. by distributing the solid fuel units throughout the growing areas in advance of freezing temperature periods. The solid fuel is then ready for use at any time without the disadvantages associated with other solid and liquid fuels previously used to avoid frost damage.

I claim:

A combustible article of manufacture consisting of the combination of:

(A) a hydrocarbon wax having a melting point of about 100-120 F. and an oil content of about 26%; and

(B) an oiland water-resistant paper container therefor, said container being an open top cylindrical polyolefin-coated paper container, consisting of a cylindrical wall of about 30-50 point long fiber kraft paper and a bottom of about 80-100 pointlong fiber kraft paper;

said wax and said paper container having differential burning rates after ignition so that said container burns at a 3 lesser rate to provide a reservoir for molten wax during 1,960,288 the combustion thereof. 2,168,698 2,276,220 References Cited 2,671,330 UNITED STATES PATENTS 5 2,825,635

496,376 4/1893 Babitt 47-2 1,357,314 11/1920 Cobb 472 Sherman 6722 X Bunt et a1. 6722 Le Veille 12659.5 X

Ajello 6721 Dooley et a1 6722 X CHARLES J. MYHRE, Primary Examiner. 

